1. Field of the Invention
The present invention relates to an information reproducing apparatus for and method of reproducing contents information recorded on a recording medium such as a CD (Compact Disc), an MD (Mini Disc), a DVD or the like. The present invention also relates to a drive control system suitable for controlling a driving device of an optical pickup in the information reproducing apparatus.
2. Description of the Related Art
Recently, there have been provided recording media such as CDs, MDs, DVDs and the like as well as corresponding players or reproducing apparatuses for reproducing those recording media. As a player among those, it is getting popular a type of indoor-use player for listening to music or watching a movie, or a type of on-vehicle player to be mounted and utilized on a vehicle. The latter allows the user to listen to music or watch a movie via one or more speakers provided for a conventional car audio equipment, or via a display screen provided for a car navigation system.
Particularly, DVDs are becoming dominant in these recording media, by virtue of their capability to store a great volume of contents information, such as video and/or audio information (e.g. voice and image information etc., in the volume for one whole movie.), on one disc.
Such DVDs can be reproduced, as mentioned below, by a DVD player as one example of the information reproducing apparatus. That is, a DVD is mounted on a trey, which is provided for the DVD player, and is then inserted thereinto. The DVD inserted into the player is then clamped. The clamping operation is carried out by holding an inner circumference of a circular hole formed at the center of the DVD by means of one or more clamping pawls each of which extends through the hole from one side of the DVD to the other side. Next, the clamped DVD is rotated with the rotational force generated by a spindle motor. In this case, the rotational movement is stable, because the DVD is held by the clamping pawls. During the rotational movement of the DVD, the reproduction of the DVD) can be carried out by reading information recorded on an information recorded surface of the DVD via the optical pickup disposed opposite to the information recorded surface.
Such information reproducing apparatuses involve, however, a problem as follows in the DVD clamping function during a series of operation. That is, such an operation of the clamping pawls is typically operatively linked to the movement of the optical pickup. More concretely, as the optical pickup moves inwardly in the radial direction of the DVD, the clamping pawls moves to disengage themselves from the DVD owing to the operative linkage therebetween.
This operative linkage can be realized in an arrangement of (i) a spring for applying force or pressure to the clamping pawls in a clamping direction (i.e. a direction in which the clamping pawls extend through the hole and hold the inner circumference of the hole.) and (ii) a clamping pawl actuating lever constructed so as to transmit the force generated by the movement of the optical pickup to the clamping pawls In this arrangement, the DVD clamp-releasing can be accomplished by the operative linkage in that the clamping pawls are displaced in a clamp-releasing direction (i.e. a direction wherein the clamping pawls are disengaged from the hole) against the applied force of the spring, via the clamping pawl actuating lever, by moving the optical pickup inwardly in the radial direction of the DVD. Similarly, the clamping pawls may be displaced in the clamping direction with a natural force of the spring, by moving the optical pickup outwardly in the radial direction of the DVD from the present position.
In this arrangement, however, the DVD may be disengaged because of the operative linkage between the clamping pawls and the optical pickup even during the DVD reproduction process. For instance, the DVD may be disengaged from its clamping position, as the optical pickup moves inwardly in the radial direction of the DVD during the rotational movement of the DVD in the case that the tracking error signal cannot be detected during the DVD track search due to an external disturbance such as a vibration, a scratch or flaw on the DVD surface. In this situation, it is hardly possible to maintain the stable rotation of the DVD, resulting in the secure reproduction process of the DVD being impossible.
To address this problem, there have been provided a sensor for sending a signal to immediately stop the carriage motor for driving the optical pickup if the optical pickup is ready to advance beyond the limit point. Alternatively, a similar sensor may be provided for the clamping pawl actuating lever to immediately stop the spindle motor if any unexpected motion of the clamping pawl actuating lever is detected. However, this does not provide the essential solution, because it takes a considerable time to set up again (resume) the reproduction process from the time of the emergency stop, and thereby may cause so-called “sound interruption” inconvenient to the user.
This problem is common in the disc shaped recording media such as CDs or MDs as previously mentioned as well as DVDs.